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RRawFileDavix.hxx
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1// @(#)root/io:$Id$
2// Author: Jakob Blomer
3
4/*************************************************************************
5 * Copyright (C) 1995-2018, Rene Brun and Fons Rademakers. *
6 * All rights reserved. *
7 * *
8 * For the licensing terms see $ROOTSYS/LICENSE. *
9 * For the list of contributors see $ROOTSYS/README/CREDITS. *
10 *************************************************************************/
11
12#ifndef ROOT_RRawFileDavix
13#define ROOT_RRawFileDavix
14
15#include <ROOT/RRawFile.hxx>
16#include <ROOT/RStringView.hxx>
17
18#include <cstddef>
19#include <cstdint>
20#include <memory>
21
22namespace ROOT {
23namespace Internal {
24
25struct RDavixFileDes;
26
27/**
28 * \class RRawFileDavix RRawFileDavix.hxx
29 *
30 * The RRawFileDavix class provides read-only access to remote non-ROOT files. It uses the Davix library for
31 * the transport layer. It instructs the RRawFile base class to buffer in larger chunks than the default for
32 * local files, assuming that remote file access has high(er) latency.
33 */
34class RRawFileDavix : public RRawFile {
35private:
36 std::unique_ptr<Internal::RDavixFileDes> fFileDes;
37
38protected:
39 void OpenImpl() final;
40 size_t ReadAtImpl(void *buffer, size_t nbytes, std::uint64_t offset) final;
41 void ReadVImpl(RIOVec *ioVec, unsigned int nReq) final;
42 std::uint64_t GetSizeImpl() final;
43
44public:
45 RRawFileDavix(std::string_view url, RRawFile::ROptions options);
47 std::unique_ptr<RRawFile> Clone() const final;
48 int GetFeatures() const final { return kFeatureHasSize; }
49};
50
51} // namespace Internal
52} // namespace ROOT
53
54#endif
The RRawFileDavix class provides read-only access to remote non-ROOT files.
std::unique_ptr< Internal::RDavixFileDes > fFileDes
int GetFeatures() const final
Derived classes shall inform the user about the supported functionality, which can possibly depend on...
void ReadVImpl(RIOVec *ioVec, unsigned int nReq) final
By default implemented as a loop of ReadAt calls but can be overwritten, e.g. XRootD or DAVIX impleme...
size_t ReadAtImpl(void *buffer, size_t nbytes, std::uint64_t offset) final
Derived classes should implement low-level reading without buffering.
std::unique_ptr< RRawFile > Clone() const final
Create a new RawFile that accesses the same resource. The file pointer is reset to zero.
std::uint64_t GetSizeImpl() final
Derived classes should return the file size or kUnknownFileSize.
void OpenImpl() final
OpenImpl() is called at most once and before any call to either DoReadAt or DoGetSize.
The RRawFile provides read-only access to local and remote files.
Definition RRawFile.hxx:43
static constexpr int kFeatureHasSize
GetSize() does not return kUnknownFileSize.
Definition RRawFile.hxx:52
tbb::task_arena is an alias of tbb::interface7::task_arena, which doesn't allow to forward declare tb...
Used for vector reads from multiple offsets into multiple buffers.
Definition RRawFile.hxx:71
On construction, an ROptions parameter can customize the RRawFile behavior.
Definition RRawFile.hxx:59